Kinetic EPR-Studies of the Anti-Peroxyl Radical Reactivities with Various Metallochelates of 3,5-Di-Iso-Propylsalicyalte
- PDF / 1,740,713 Bytes
- 21 Pages / 439.37 x 666.142 pts Page_size
- 97 Downloads / 157 Views
Applied Magnetic Resonance
REVIEW
Kinetic EPR‑Studies of the Anti‑Peroxyl Radical Reactivities with Various Metallochelates of 3,5‑Di‑Iso‑Propylsalicyalte and Salicylidene Schiff Base Levon A. Tavadyan1 · Makich V. Musaelyan1 · Armine B. Stepanyan1 · Seyran H. Minasyan1 Received: 11 June 2020 / Revised: 25 July 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Copper(II)-, Fe(III)-, Zn(II)-, and Mn(II)-3,5-di-iso-propylsalicylate (3,5-DIPS) chelates and Cu(II)2(acetyl-3,5-DIPS)4, and 3,5-DIPS, salicylidene Schiff base chelates Mn(III), Co(II), Ni(II), were kinetically examined as antioxidants in the scavenging of tert-butyl peroxyl radical ( tert − butylOO∙ ) in non-polar and polar aprotic solvents. Using kinetic EPR method absolute rate constants and corresponding Arrhenius parameters were determined for reactions of tert − butylOO∙ with these chelates in the temperature range from − 63 to − 11 °C. It was established that the order of anti-tert − butylOO∙ reactivity is: Mn(II)(3,5-DIPS)2 >> Cu(II)2(3,5-DIPS)4 > Fe(III) (3,5-DIPS)3 > Zn(II)(3,5-DIPS)2 >> Cu(II)2(acetyl-3,5-DIPS)4 and 3,5-DIPS acid. Mn(II)(3,5-DIPS)2 caused the most rapid removal rate for tert − butylOO∙ as a result of the oxidation of Mn(II) to Mn(III) by tert − butylOO∙ . The reaction of tert − butylOO∙ with Cu(II)2(3,5-DIPS)4, Zn(II)(3,5-DIPS)2 and Fe(III)(3,5-DIPS)3 is due only to hydrogen atom abstraction from the ligand phenolic OH group by tert − butylOO∙ , owing to their activation by the metalloelement through weakening the intramolecular hydrogen bond. High reactivity of tert − butylOO∙ with Mn(III) and Co(II) salicylidene Schiff base chelates was established. These salicylidene Schiff base chelates react in a 1:1 stoichiometric ratio with tert − butylOO∙ without free radical formation and with the single-electron oxidation of central metalloelements. It is concluded that removal of alkylperoxyl radical by Cu(II)-, Fe(III)-, Zn(II)-, and Mn(II)-3,5-di-iso-propylsalicylate chelates, Mn(III) and Co(II) salicylidene Schiff base chelates may partially account for their biological activities.
* Levon A. Tavadyan [email protected] 1
Institute of Chemical Physics, National Academy of Sciences, 5/2, P. Sevak Street, 0014 Yerevan, Republic of Armenia
13
Vol.:(0123456789)
L. A. Tavadyan et al.
1 Introduction It has been clearly shown that essential metalloelement (Cu, Fe, Zn, Ni, Co and Mn) chelates exhibit properties of efficient bioactive antioxidants with potential for the prevention and/or treatment of various pathological disease states [1–7]. These co-ordination compounds show a great diversity in action. Metal coordination can be used to enhance the activity of biologically active molecules. These activities have been related to their superoxide dismutase (SOD)-mimetic, catalase-mimetic, P450 modulating, protein kinase modulating, cyclo-oxygenase modulating, and nitric oxide synthase modulating activities as well as their respective facilitation of specific metalloelement-dependent enzyme synthes
Data Loading...
